I found this discussion of the Apple v. Epic ruling to be informative:
> as discussed in the findings of facts, IAP is the method by which Apple collects its licensing fee from developers for the use of Apple’s intellectual property. Even in the absence of IAP, Apple could still charge a commission on developers. It would simply be more difficult for Apple to collect that commission.
Indeed, while the Court finds no basis for the specific rate chosen by Apple (i.e., the 30% rate) based on the record, the Court still concludes that Apple is entitled to some compensation for use of its intellectual property.
https://stratechery.com/2021/the-apple-v-epic-decision/
The judge hinted here and there that Epic should have sued over the size of Apple's cut, not it's right to take a cut.